Mutational Analysis of Mycobacterial F-ATP Synthase Subunit δ Leads to a Potent δ Enzyme Inhibitor.

While many bacteria are able to bypass the requirement for oxidative phosphorylation when grown on carbohydrates, Mycobacterium tuberculosis is unable to do so. Differences of amino acid composition and structural features of the mycobacterial F-ATP synthase (α 3 :β 3 :γ:δ:ε: a : b : b' : c 9 ) compared to its prokaryotic or human counterparts were recently elucidated and paved avenues for the discovery of molecules interfering with various regulative mechanisms of this essential energy converter. In this context, the mycobacterial peripheral stalk subunit δ came into focus, which displays a unique N-terminal 111-amino acid extension. Here, mutants of recombinant mycobacterial subunit δ were characterized, revealing significant reduction in ATP synthesis and demonstrating essentiality of this subunit for effective catalysis. These results provided the basis for the generation of a four-feature model forming a δ receptor-based pharmacophore and to identify a potent subunit δ inhibitor DeMF1 via in silico screening. The successful targeting of the δ subunit demonstrates the potential to advance δ's flexible coupling as a new area for the development of F-ATP synthase inhibitors.